Catalytic dehydration of alcohols using phase pure, calcined single- and multi-site heterogeneous catalysts

Abstract

The disclosure describes a new class of isomorphously metal-substituted aluminophosphate materials with high phase purity that are capable of performing selective Brönsted acid catalyzed chemical transformations, such as transforming alcohols to olefins, with high conversions and selectivities using mild conditions. Isomorphous substitutions of functional metal ions for both the aluminum ions and the phosphorous ions were successful in various AlPO structures, along with multiple metal substitutions into a single aluminum site and/or a phosphorous site. This invention can be used towards the catalytic conversion of hydroxylated compounds of linear and/or branched moiety with the possibility of being substituted to their respective hydrocarbon products, preferably light olefins containing 2 to 10 carbon atoms, among other chemistries.

The claimed invention is: 
     
       1. A substantially phase pure, calcined aluminophosphate, AlPO 4 , wherein at least one aluminum (Al III ) site is isomorphously metal-substituted by a divalent metal ion (M II ) or at least one phosphorous (P V ) site is isomorphously metal-substituted by a tetravalent metal ion (M IV ). 
     
     
       2. An aluminophosphate of  claim 1 , wherein the divalent metal ion is selected from the group consisting of Zn II , Mg II , Co II , Ca II , Ni II , Pd II , and mixtures thereof and the tetravalent metal ion is selected from the group consisting of Si IV , Zr IV , Pt IV , Sn IV , Ti IV , Ge IV , Pd IV , a and mixtures thereof. 
     
     
       3. An aluminophosphate of  claim 2 , wherein the molar amount of M II  substituted for Al III  ranges from about 0.001 to about 0.10 moles M II  and the molar amount of M IV  substituted for P V  ranges from about 0.01 to about 0.25 moles M IV . 
     
     
       4. An aluminophosphate of  claim 1  having a pore size ranging from about 3 Ångstroms to about 15 Ångstroms. 
     
     
       5. An aluminophosphate of  claim 1  wherein the aluminophosphate has an AlPO-5 framework, an AlPO-18 framework, an AlPO-34 framework, or an AlPO-36 framework. 
     
     
       6. An aluminophosphate of  claim 2  selected from the group consisting of Mg II Si IV  AlPO-5, Zn II Si IV AlPO-18, Zn II Si IV AlPO-5, Zn II Ti IV AlPO-18, Mg II Si IV Zn II AlPO-5, Mg II Ti IV AlPO-36, Mg II Si IV AlPO-18, Mg II Ti IV AlPO-5, Zn II Si IV AlPO-5, Zn II Ti IV AlPO-36, Mg II Si IV AlPO-34, Mg II Si IV AlPO-18, and Mg II Si IV AlPO-5. 
     
     
       7. An aluminophosphate of  claim 2  selected from the group consisting of Si IV AlPO-5, Ti IV AlPO-36, Ti IV AlPO-5, Si IV AlPO-34, Si IV AlPO-18, Ti IV AlPO-36, Si IV AlPO-5, Si IV AlPO-18, Ti IV AlPO-18, Ti IV AlPO-34, Si IV AlPO-5, Si IV AlPO-18, Si IV AlPO-36, Mg II AlPO-5, Zn II AlPO-18, Mg II AlPO-36, Mg II AlPO-34, Zn II AlPO-5, Mg II AlPO-34, Zn II AlPO-36, Mg II AlPO-18, and Mg II AlPO-5. 
     
     
       8. The substantially pure, calcined aluminophosphate of  claim 1  having an X-ray diffraction pattern with an observed 2Theta position for each peak that is less than 0.1000° different from a respective calculated 2Theta position for each said peak. 
     
     
       9. A substantially phase pure, calcined aluminophosphate, AlPO 4 , wherein at least one aluminum (Al III ) site is isomorphously metal-substituted by a divalent metal ion (M II ) and at least one phosphorous (P V ) site is isomorphously metal-substituted by a tetravalent metal ion (M IV ). 
     
     
       10. An aluminophosphate of  claim 9 , wherein the divalent metal ion is selected from the group consisting of Zn II , Mg II , Co II , Ca II , Ni II , Pd II , and mixtures thereof and the tetravalent metal ion is selected from the group consisting of Si IV , Zr IV , Pt IV , Sn IV , Ti IV , Ge IV , Pd IV , and mixtures thereof. 
     
     
       11. An aluminophosphate of  claim 10 , wherein the molar amount of M II  substituted for Al III  ranges from about 0.001 to about 0.10 moles M II  and the molar amount of M IV  substituted for P V  ranges from about 0.01 to about 0.25 moles M IV . 
     
     
       12. An aluminophosphate of  claim 9  having a pore size ranging from about 3 Ångstroms to about 15 Ångstroms. 
     
     
       13. An aluminophosphate of  claim 9  wherein the aluminophosphate has an AlPO-5 framework, an AlPO-18 framework, an AlPO-34 framework, or an AlPO-36 framework. 
     
     
       14. An aluminophosphate of  claim 10  selected from the group consisting of Mg II Si IV AlPO-5, Zn II Si IV AlPO-18, Zn II Si IV AlPO-5, Zn II Ti IV AlPO-18, Mg II Si IV Zn II AlPO-5, Mg II Ti IV AlPO-36, Mg II Si IV AlPO-18, Mg II Ti IV AlPO-5, Zn II Si IV AlPO-5, Zn II Ti IV AlPO-36, Mg II Si IV AlPO-34, Mg II Si IV AlPO-18, and Mg II Si IV AlPO-5. 
     
     
       15. An aluminophosphate of  claim 10  selected from the group consisting of Si IV AlPO-5, Ti IV AlPO-36, Ti IV AlPO-5, Si IV AlPO-34, Si IV AlPO-18, Ti IV AlPO-36, Si IV AlPO-5, Si IV AlPO-18, Ti IV AlPO-18, Ti IV AlPO-34, Si IV AlPO-5, Si IV AlPO-18, Si IV AlPO-36, Mg II AlPO-5, Zn II AlPO-18, Mg II AlPO-36, Mg II AlPO-34, Zn II AlPO-5, Mg II AlPO-34, Zn II AlPO-36, Mg II AlPO-18, and Mg II AlPO-5. 
     
     
       16. The substantially pure, calcined aluminophosphate of  claim 9  having an X-ray diffraction pattern with an observed 2Theta position for each peak that is less than 0.1000° different from a respective calculated 2Theta position for each said peak. 
     
     
       17. A process for the dehydration of alcohols to form olefins, comprising the step of:
 contacting a feedstock containing an alcohol with an aluminophosphate of  claim 1  or  9  under conditions sufficient to convert the alcohol to an olefin. 
 
     
     
       18. A process of  claim 17 , wherein the alcohol is a C 2 -C 10  alcohol. 
     
     
       19. A process of  claim 17 , wherein the feedstock is contacted with the aluminophosphate at a temperature ranging between about 23° C. and about 700° C. 
     
     
       20. A process of  claim 17 , wherein the feedstock is contacted with the aluminophosphate at a temperature ranging between about 50° C. and about 250° C. and at a pressure of 1 atmosphere to 30 atmospheres. 
     
     
       21. A process of  claim 19 , wherein the alcohol is a liquid. 
     
     
       22. A process of  claim 21 , wherein ethanol is converted to ethylene, propanol is converted to propylene, t-butyl alcohol is converted to isobutylene, or methyl benzyl alcohol is converted to styrene. 
     
     
       23. A process for preparing a substantially phase pure, calcined metal-substituted aluminophosphate, AlPO, wherein at least one aluminum (Al III ) site is substituted by a divalent metal ion (M II ) and/or at least one phosphorous (P V ) site is substituted by a tetravalent metal ion (M IV ), comprising the steps of:
 adding a phosphorous source to water to form an aqueous mixture, 
 stirring the aqueous mixture, 
 adding an aluminum source to the stirred aqueous mixture to form a first reaction mixture, 
 adding at least one aqueous solution or suspension of a M II  metal source, M IV  metal source, or both to the stirred first reaction mixture, 
 stirring the first reaction mixture containing the metal source for a time sufficient to form a homogenized mixture, 
 optionally adding a further quantity of water to the stirred homogenized mixture, 
 adding a structure directing agent to the stirred homogenized mixture to form a second reaction mixture, 
 optionally adding water, 
 stirring the second reaction mixture until the reaction is complete to form a substituted AlPO reaction product mixture, 
 aging the substituted AlPO reaction product mixture, 
 autoclaving the aged substituted AlPO reaction product mixture in a high pressure autoclave unit equipped with resistant liners at a temperature ranging between about 23° C. and about 500° C. for up to about 6 hours, 
 quenching the autoclave, 
 filtering the autoclaved substituted AlPO reaction product mixture to recover a solid catalyst product, 
 washing the solid catalyst product with water, 
 drying the solid catalyst product, 
 slowly heating the dried catalyst product under a flowing inert gas at a calcination temperature ranging between about 200° C. and about 1000° C., 
 holding the dried catalyst product under the flowing inert gas at the calcinations temperature, 
 calcining the dried catalyst product for a time of at least about 3 to about 24 hours to form a substantially phase pure, calcined metal-substituted aluminophosphate, and 
 slowly cooling the substantially phase pure, calcined metal-substituted aluminophosphate to room temperature. 
 
     
     
       24. A process of  claim 23 , wherein the inert gas is nitrogen and the calcining step comprises calcining under a flow of dry air. 
     
     
       25. A process for preparing a substantially phase pure, calcined metal-substituted aluminophosphate, AlPO, wherein at least one aluminum (Al III ) site is substituted by a divalent metal ion (M II ) and/or at least one phosphorous (P V ) site is substituted by a tetravalent metal ion (M IV ) comprising the steps of:
 slowly heating an isomorphously, metal-substituted aluminophosphate catalyst product containing a structure directing agent within its crystalline structure under a flowing inert gas at a calcination temperature ranging between about 200° C. and about 1000° C., 
 holding the isomorphously, metal-substituted aluminophosphate catalyst product under the flowing inert gas at the calcination temperature, 
 calcining the isomorphously, metal-substituted aluminophosphate catalyst product for a time of at least about 3 to about 24 hours to form a substantially phase pure, calcined metal-substituted aluminophosphate, and 
 slowly cooling the substantially phase pure, calcined metal-substituted aluminophosphate to room temperature. 
 
     
     
       26. A process of  claim 25 , wherein the inert gas is nitrogen and the calcining step comprises calcining under a flow of dry air.